The present invention relates to a method of producing cast iron and to the apparatus for performing such a method.
It is already known to produce cast iron by melting scrap, sponge iron and similar iron-containing metallic substances, such as by melting such metallic substances by means of an oxidizing flame, and to subsequently enrich the molten metallic substance with carbon, alloying elements and the like and additionally heat the enriched metallic substance.
For the production of cast iron for use in casting installations, it has been already proposed to utilize cupola ovens which are heated either by means of coke or of natural gas, and to utilize scrap, raw iron, casting scrap, sponge iron and similar metallic substances as the starting materials. Relatively large amounts of coke are to be employed in a coke-heated cupola oven, and a relatively long transient time period is required at the beginning of the operation of the cupola oven before the cupula oven operates according to the required parameters. During such transient time periods, there is produced a substantial amount of intermediate iron of low quality. In addition thereto, during the production of cast iron in such a cupola oven, the iron-containing metallic substance acquires a substantial amount of sulphur, and the degree of enrichment of the metallic substance by carbon cannot be controlled, so that the flowable metal must be separated from the slag and must be subsequently further treated. Even when the cupola oven is operated by utilizing natural gas for heating the interior thereof, there remains the necessity to provide a treating vessel, such as an induction or an electric arc discharge oven downstream of the cupola oven, in which the molten metallic material is enriched with carbon, alloyed and further heated to a required temperature. Inasmuch as electric energy is consumed during such further treatment, and an expensive aftertreatment vessel is required, this process is very expensive.